There are many different ways of cooking rice, and you might not want to use a rice cooker if you really want individual grains, as it was developed for cuisines / rice varieties that are stickier.
Although moscafj mentioned basmati, which is a very long grain variety of rice that's from India, and tends to cook up less sticky ... you might also consider "parboiled" rice which tends to not stick together at all. But I suspect that you would have to vary the amount of water used so it doesn't become a big glob.
There's a technique of cooking rice in which you cook it like pasta -- in a large amount of water, and then drain it. This should reduce surface starch and prevent it from clumping. There are variations on this where you boil it part way, drain it, then steam to finish (possibly fluffing it up as it steams to make sure it doesn't develop clumps)
And then there's pilaf / plau / pulao style of cooking rice ... in which you first cook the rice (and possibly some finely diced vegetables, or even meat) in some oil or butter, then add the water, cover, and bake it. This tends to result in more individual grains of rice, provided you don't develop a socarrat / tahdig (the crispy layer of rice at the bottom of the pot, like in paella making).
If you're really set on using a rice cooker, I would specifically put in less water than it called for, and then check the rice once it switches over to warm, and check to see if it's cooked through. If it isn't, I'd add a little more water and turn it back on. (mechanical switch rice cookers might need a minute or two to cool before you can turn it back to 'cook', due to how the mechanism works).
Once it's cooked through, use a fork to 'fluff' the rice, dumping the loosened rice into a sheet pan, casserole pan, directly onto people's plates, or some other wide vessel that lets you spread out the rice without it being too deep.) If you see any clumps, use your fork to break it up, or clean hands to try to 'rub' grains apart like you would couscous.